Can't compile C program on a Mac after upgrade to Mojave

Question

I have used the gcc command on the terminal to compile C programs but all of a sudden, after an update to my Mac\'s OS (to macOS 10.14 Mojave, and XCode 10.0), I started rec

Answer 1

I tried almost all the posted solutions and nothing worked for me. I use Mojave OS (10.14.6) and what finally worked for me (after removing and re-installing Xcode and CLTs and SDK headers):

1. Install Clang v8 from https://cran.r-project.org/bin/macosx/tools/
2. Modify the following lines from ~/.R/Makevars file

CC=/usr/local/opt/llvm/bin/clang -fopenmp
CXX=/usr/local/opt/llvm/bin/clang++

with

CC=/usr/local/clang8/bin/clang -fopenmp
CXX=/usr/local/clang8/bin/clang++

Now R packages that rely on C compilers install successfully